Silicone Brake Fluid

[Don Z.]

I was looking in the archives regarding changing my system over to DOT 5.
There are many ideas and thoughts but most were to be done when a new system is being introduced to the car.
Are there any articles written regarding a complete procedure on how to convert over?
Can I dis-connect my master, bench bleed the master with DOT5, blow out the lines, put alcohol in and flush all out a few times? Do I need to completly tear apart the system?
Being a novice at this, any help is appreciated, or maybe I may have to leave it as it is. Thank You

[David K.]

Re: Silicone Brake Fluid

This is what I did. Others I am sure have done it other ways. I first almost emptied the master cylinder of any and all brake fluid. The I started putting in the silicone fluid and bleeding the closests brakes first. When I was all done, I did it all again, making sure I again replaced all the silicone fluid. The next spring I bled it all again. I never had any problems. That was 20yrs. ago. This year I did replace all metal and rubber brake lines, actually just for cosmetic reasons, but also safety. I didn't see any problems having done it the way I did it.

[Lyndon S.]

Re: Silicone Brake Fluid

So you just kept flushing dot 5 through the system? And you did not do a alcohol flush? And your brake system was old and using dot 3?

[David K.]

Re: Silicone Brake Fluid

Yes, it was an old brake system on Dot 3 and I did not use any alcohol. I just used the Dot 5 for my flushing agent.

[Lyndon S.]

Re: Silicone Brake Fluid

I wonder how many people have done that , just flushing with new dot5 and not had any trouble in a C2-3 with disk brakes? I would like to hear others on here that have had similar success doing it that way.

[Mike M.]

Re: Silicone Brake Fluid

I switched to DOT 5 fluid about 15 years ago on my 62, I replaced the 3 rubber brake lines and all the steel brake line. I also replaced the master and wheel cylinders with new parts. I never disassembled, cleaned and reassembled the master and wheel cylinders with DOT 5 fluid. It's been 15 years and I've never have had a problem.
Search "Battle of the Dots" good article about DOT 3, 4 & 5 and their differences.
It's all about compatibility.
Mike

[Jim L.]

Re: Silicone Brake Fluid

I wonder how many people have done that , just flushing with new dot5 and not had any trouble in a C2-3 with disk brakes? I would like to hear others on here that have had similar success doing it that way.

I'm one of the ones who has successfully converted a car to silicone fluid without going to the trouble to exhaustively flush out the old DOT 3 fluid.

See that blue and white car in my avatar? When we got that car, I did the conversion to silicone fluid and ever since, it's been my wife's track car (Laguna Seca, Sears Point, Thunderhill, etc).

We've had no problems with the brakes, even if there are small traces of DOT 3 still hiding in the far corners of the system.

Jim

[Terry M.]

Re: Silicone Brake Fluid

There is an SAE (Society of Automotive Engineers) paper precisely about this practice. The experiments were done on military vehicles in the '60s. One of the DOT5 vendors (I believe it was STP) recommended this method on their containers of DOT5.

The SAE paper found a black residue inside the brake systems that had been flushed with DOT5. I think there were performance tests that measured a longer stopping distance for systems with just the flush through method, against both DOT 3/4 and cleaned DOT5 systems. My best recollection is the performance tests they did are likely exceed anything we are likely to do with our old Corvettes. I would have to dig out the paper to be absolutely sure of the results -- but I am sure the bottom line of the paper was not to do it that way. They concluded removal of ALL the glycol based fluid before introducing the DOT5 was essential to prevent this black jelly-like material from forming.

Edit add: I am pretty sure this is the paper:

http://www.sae.org/technical/papers/860633

[Lyndon S.]

Re: Silicone Brake Fluid

One more question on switching over to silicone brake fluid. Where is the best place to get it, most of the parts stores only carry the small 11oz size.

I bought a new reproduction master cylinder for my car recently , and had thought about switching over to DOT5. If I just bench bleed the master and use DOT5 for the flushing, how much fluid will I need to do the job?

[Walt W.]

Re: Silicone Brake Fluid

I bought a quart from NAPA. Cost $ 35.00.

Walt Weems

[Harmon C.]

Re: Silicone Brake Fluid

This question comes up all the time as to how clean the system must be to change to dot 5. Some will say you need to tear apart new rebuilt calipers that were assembled with dot 3 or your system will fail. Before I learned all thease facts on the internet I put on a new set of calipers and hoses only let the dot 5 run till I could see the blue fluid and hooked up the hose to each caliper. That was 1990 and the brakes have worked fine with no problems.
I have not cracked a bleader on this system for 18 years and won't unless I see a leak or the pedal gets soft. I say if you have good brakes on a Corvette leave them alone.

[Lyndon S.]

Re: Silicone Brake Fluid

I bought a new reproduction master cylinder for my car recently , and had thought about switching over to DOT5. If I just bench bleed the master and use DOT5 for the flushing, how much fluid will I need to do the job?

[Gary B.]

Re: Silicone Brake Fluid

When I changed my `62 from DOT 3 to DOT 5 I did the "Flush and Fill" and wrote an article for the Restorer around 1996. I included photos of the "Black residue" after about 6 months when I did another "Flush and Fill" with DOT 5.
The last time I did a "Flush and Fill" it was clear.
When I did it the First time I replaced all the rubber hoses.
I still have the full SAE (Society of Automotive Engineers) paper somewhere in my files, which I sent a copy to Terry.

[Paul C.]

Re: Silicone Brake Fluid

I switched my 71 LT-1 to silicone after changing to SS brake lines, had PB booster rebuilt, new MC, and new lines. Bought 2 quarts of silicone from paragon $21.60/qt--used about 1.5 quarts. Brakes feel great and I don't have to worry about moisture and it breaking down. Used Motive power bleeder--bench bleed the MC, tapped cylinders with rubber hammer and bleed out in proper sequence. Glad I did it--now no worries again. Paul

[Grant M.]

Re: Silicone Brake Fluid

When I bought my car in 1987 it had been disassembled, the M/C had been removed as had all of the rubber brake hoses. The original calipers had all been SS sleeved and had not been installed on the car. I bought a new M/C, a couple of new steel lines for the front end, and all new rubber lines. I took the car to a brake shop to have the brake system (M/C, calipers, rubber hoses, pads, etc) installed and converted to silicone. I confess that at the time I didn't know/didn't specify exactly what they were to do or how they should flush etc. the system (and there wasn't any TDB to ask either). In any event, it's been 21+ years since then and my brakes (manual) work fine with never a leak or soft pedal. My guess is that whatever DOT 3 was left in the original lines on the car either leaked or was blown/flushed out by the brake shop and replaced with silicone. I guess I should probably replace the fluid soon...(another 'confession').

grant